Eyeglass lens



EYEGLASS LENS Edward Culver and Alfred Henry Emerson, London,- England,assignors to United Kingdom Optical Company, Limited, London, EnglandApplication October 9,

1934, Serial No. 747,576

In Great Britain June 27, 1934 9 Claims.

This invention relates to eyeglass lenses, generally known as ophthalmiclenses, and especially to lenticular ophthalmic lenses wherein thethickness of high-powered lenses is reduced by the provision of a smalldiameter lens portion surrounded by a non-visual portion known as thecarrying border` One object of our invention is 'to provide a lenticularophthalmic lens having multiple elds of the same power, so as to stillfurther reduce the thickness required for a high-powered concave orconvex lens as compared to the thickness required for an ordinarylenticular lens.

Another object is to provide a lenticular ophthalmic lens having acentral field and other elds of the same power adjacent to the centralfield, thereby forming a plurality of visual fields whose size overallis much elongated in on'e direction. 20 Another object is to provide alenticular ophthalmic lens having a plurality of visual elds arrangedadjacent to one another horizontally, these elds being of the same powerand enabling the wearer to obtain a wide angle of view in a horizontaldirection without requiring the angle of view in the vertical directionto be unnecessarily increased.

Another object is to provide a bifocal lenticular lens having elds ofthe above description toadapt it fornboth distant and near vision, thisbifocal being either of a one-piece or fused construction.

Another object is to provide a lenticular oph thalmic lens having aplurality of fields of the same visual powers but withdiierently-located ophthalmic centers, and surrounded by a nonvisualportion.

Another object is to provide a method of mak- This invention is for thepurpose of providing" an improved lens for the correction of strongmyopie and hyperopic errors of refraction. 'It

gether with a field of diierent power, so as to ing a lenticular concavelens consisting of pre-- is well known that many of the lenses atpresent in usefor the'correction of these high errors are very thick,heavy, ugly in appearance and often, owing to the curvatures employedgive poor vision except at the very centre of the lens. It is the 5purpose of this invention to` reduce the weight and to improve theappearance and optical per` formance of these high power lenses.

One method of obtaining some reduction in the weight of these lenseswhich is at present in 10 use is to make them in lenticular form. Thisis done by removing glass from the peripheral portions of the lens bygrinding a dilerent curve on the margin of the lens from that at thecenter. This has the elect of cutting down the field ol 15 view and anygreat saving in weight can only be obtained by still further reducingthe eld. Further, at the edge of the field of these lenses considerableaberrations occur and there is a large deviation of the line of sight onpassing 20 through the lens. This deviation or prismatic effect isoutwards withv concave lenses and inwards with convex and increases asthe line of sight moves away from the optical center of the lens.

Now in ordinary everyday vision the excursions of the eye from itsposition of rest are greatest and most frequent in the horizontalmeridian. This invention 4provides lenses which are lighter in weightand which also have a wider horizontal 30V field of view with lessprismatic effect than those at present in use.

This is accomplished by dividing the horizontal eld into three or moreportions each with its own optical center.

In the drawing:

Figure 1 is an elevational View of a single power lenticular concavelens according to my invention;

Figure 2 is a central vertical section along the 40 line 2-2 of Figure1;

Figure 3 is a central horizontal section along the line 3--3 of Figure1, the dotted lines showing the thickness required for the lens if asingle lenticular portion were used instead of the 'mul- 45 t-iplelenticular portions provided by my invention; Y

Figure 4 is an elevational view of a singlepower convex lenticular lensaccording to my invention; 50

Figure 5 is a central vertical section along the line 5 5 of Figure 4;

Figure 6 is a central horizontal section along the line 6--6 of Figure4, the dotted lines showing the thickness which would be required for 55the lens if a single lenticular portion were used instead of themultiple lenticular portions of my invention;

Figure '7 is an elevational view of a lenticular concave bifocal made oftwo kinds of glass fused together;

Figure 8 is a central vertical section along the line 8--8 of Figure '1;

Figure 9 is an elevational view of a lenticular concave bifocal lensmade from the same kind of glass throughout, but having differentsurface curvatures to provide the differently-powered reading portion;

Figure 10 is a central vertical section along the line Ill- IIJ ofFigure 9;

Figure 11 is an elevational view of a lenticular `convex bifocal lensaccording to my invention;

Figure 12 is a central vertical section along the line I2-l2 of Figureil.

Figure 13 is an elevation of a modied form of lens with an insert on theside opposite the ground surface having a plurality of grounddepressions.

Figure 14 is a section on the line I4-I4 of' Figure 13.

Referring to the drawing in detail, Figure 1 shows a lenticular concavelens according to our a single lenticular area. The dotted edge I5 isinvention as consisting of a body portion, generally designated I, anddivided into a border portion 2 and a visual portion 3. The borderportion 2 is not used for vision, but is provided merely as a carryingportion to contain the visual portion 3.

The visual portion 3 consists of a plurality of areas 4, 5 land6-arranged adjacent to one another and having the same surfacecurvatures. In this manner the dividing lines 1 and 8 between theseadjacent portions are straight when viewed by an observer directly infront of the lens. The reason for this straightness depends on thegeometric fact that two spherical surfaces of the same radii ofcurvature intersect along an arc whose projection on a plane parallel totheir line of centers is a straight line. The intersecting fields 4, 5and 6, therefore, have independent optical centers 9, I and II spacedapart from one another.

To make the lenticular concave lens shown in Figure 1, a blank of glasssuicient in size to make the body portion I is ground and polished witha tool of the proper curvature to make the concavity comprising thecentral portion 4. The lens and tool may then be shifted relatively toone another and the side portions and 6 similarly ground and polished.The border portion 2 may be provided with a border surface I2 ofcurvature appropriate to give a thin edge to the lens when the outersurface I3 ,common to all elds has been ground and polished. It is notintended to imply that it is necessary to start by grinding theconcavity 4. Any other method may be adopted which produces the threefields 4, 5 and 6 in the positions shown.

In this manner, there results. a lenticular concave lens with multiplefields adjoining one another. The provision of these multiple fieldsenables the reduction of the edge thickness of the lens by aconsiderable amount. The great reduction possible by our invention isshownin Figure 3, wherein the dotted lines represent the cross sectionaldimensions of an ordinary lenticular concave lens of the same power, buthaving only of such Ithickness as to makesuch a lens unsightly;consequently it has been the practice hitherto to make the lenticularportion of small dimensions in order to vkeep this edge thickness- I5 ata minimum. By my invention, however, the lenticular area may be given avery wide extent, yet the edge thickness may be kept within limitssmaller than those of a single lenticular lens with a much smallerlenticular area. It will be seen, furthermore, that if the dotted borderportion I1 is omitted (Figure 3) and the lenticular surface be carrieddirectly out to meet the edge I5, then the latter will be still thickerand still more unsightly; this would occur in an ordinary single-visionlens without any lenticular area whatever.

Thus by the provision of the multiple lenticular areas arranged side byside, I not only provide a lens which is attractive in appearance. butalso conforms to the mechanical action of the eyes. It has been found byexperimentation and observation over a large number of cases that humanbeings use their eyes to a much greater extent in horizontal directionsthan in vertical ones. Consequently, the eyeballs are rotated through amuch wider angle of view horizontally than vertically. As a result theideal lenticular lens should have a horizontal eld which is much broaderthan the vertical eld, thus consisting in its ideal form of an elongatedarea. Such an area is provided by the lens of my invention, and withoutthe excessive thickness which the oval lenticular lens of the prior artoccasioned. In the latter form of lens, the edge thickness was largelydetermined by the greater horizontal diameter of the lens than thevertical diameter, the border portion of the lens having been con vexedwith'a tool having a torio surface so as to give' an oval outline to thecentral lenticular area.

To make a lenticular convex lens according to my invention (Figure 4),the body portion I of the lens is prepared in the manner previouslydescribed in connection with Figure 1; multiple fields or concavities20, 2l and 22 are surfaced in the body portion I, these being ofappropriate surface curvature to provide the requisite focal power,according to computations well known to those skilled in the art. Theseconcavities 20, 2l and 22 are of the same curvatures, hence, havestraight lines of joinder' therebetween, as shown by the dotted lines inFigure 4. After the concavities 20, 2l and 22 have been prepared, aglass button 23 of a higher index of refraction is then fused into thisseries of concavities. When the surface 24 is ground-over the entirelenticular side of the lens, thelatter-will be provided with portions20, 2| and 22 having much higherfocal powers than the border part of thebody portion I, due to the difference in power between the low-indexlenses which, in effect, are ground out of the body portion I andreplaced by the highindex lenses fused into the body portion. The outersurface 25 is then ground to the proper curvature to give the necessaryvisual power as in Figure 6 indicate the extra thickness required 25 bythis single lenticular portion of the prior art.

To provide a lenticular concave lens with a bifocal portion, we mayproceed in two different ways. In Figure 7 we show such a bifocal lensemploying the fused bifocal principle, wherein glass of a. differentindex of refraction is employed to provide the area. of different powerfor near vision. In Figure 9, however, we show a .bifocal lens of thesolid or one-piece type, this consisting of glass of the same index ofrefraction throughout. The one-piece bifocal of Figure 9 depends for itsaction upon the provision of a diierent surface curvature for thenear-vision portion from that of the distantvision portions of the lens.To provide a lenticular convex lens, as shown in Figure 11, we utilizethe principle of employing diierent surface curvatures in theconcavities, and then fill in the concavities with a glass .of a higherindex of refraction.

The lenticular concave fused bifocal shown in Figure 7 is preferablymade by providing the body portion with a deep eountersink curve orconcavity 3|, this being of such curvature, as computed according toprinciples well-known to those skilled in the art, as to be suitable forreading vision in the completed lens. A glass button 32-` of a higherindex of refraction is then prepared and fused in this countersink 3|.In the succeeding operations, the lens is completed by surfacing themultiple concavities 33, 34 and 35 of like curvatures in the lens inmuch the same manner as the concavities 4, 5 and 6- (Figure 1),previously described. The central concavity 33, however, and-possiblythe side concavities/34 and 35, intersect the portion of the lensoccupied by the button 32 in such a manner as to extend thereover(Figure 8). Accordingly, when the border surface 36 and the outersurface 31 have been madegthe resulting lens (Figure 7) will be providedwith distant-vision portions 33, 34 and 35, together with a near visionportion 38 forreading or other near vision.

The button 32 can, if desired, be of the composite type in'which the toppart is made from glass of the same index as the major body portion. Thetop of the reading portion may then be made sensibly straight instead ofsteeply curved. This .button insert may also be placed in the frontsurface of the lens.

The one-piece lenticular concave bifocal shown in Figure 9 is prepared,during its earlier stages of manufacture, in much the similar manner asthe single vision' lenticular concave lens shown in Figure 1. Accordingto this procedure the body portion 40 is provided with concavities 4i,42 and 43 of like curvatures suitable for the distant visionrequirements of the myopie wearer. Following this, the lens is providedwith an additional coneavity 44 adjacent to the concavities 4 I, 42 and43, but of a diierent surface curvature.` The surface curvature of theportion 44 is shallower or atter than the surface curvature of theportions 4|, 42 and 43, so that a more positive focal power is providedfor the portion 44 in order to adapt it to near vision requirements. Itwill be observed that the dividing lines 45 and 46 between the portionsof the same surface curvature are straight lines for the reasonspreviously given, whereas the dividing lines 41, 48 and 49 between theseportions and the near-vision portion 44 are curved lines, due to thedifferent surface curvature ofthe latter. The lens is then provided witha border surface 50 and an outer surface' 5I in the manner previouslydescribed.

Thus is provided a bifocal lens having a plurality of distant-visionportions intersecting *one another on straight lines, and a near-visionportien intersecting these on curved lines. All of these portions haveindependently-located optical centers. 1

AIn its early stages, the lenticular convex bifocal lens shown inFigures 11 and 12 is made in a manner somewhat similar to that of theone-piece bifocal shown in Figure 9. A body portion 69 is provided withsuitable concavities 6l, 62 and 63, whose curvatures are based upon thesame prineiples and computations discussed in connection with Figure 4.These concavities are of thesame surface curvatures and consequentlyintersect on the straight lines 64 and 65. A concavity 66 of deeper orstronger surface curvature is then' ground in such a manner as tointersect the concavities 61, 62 and 63, the intersections being alongthe curved lines 61, 68 and 69. A glass button 10 of a higher index ofrefraction is then prepared and fused into the series of concavitiespreviously described, and the exposed common surface 1| ground with acurvature suitable for the border portion 12, after which the oppositeside 13 may be surfaced in accordance with the same principles discussedin connection with Figures 4 to 6. Thus the lenticular convex bifocal ofFigures 11 and 12 consists of a plurality of 4portions adapted fordistant vision, together with a. portion suitable for near Ivision, eachof these portions having its own optical center. Consequently, thehyperopic or aphakic wearer'of this lens will be provided with distantand near vision portions suited to his own requirements.

Accordingly, we have provided a lenticular ophthalmic lens with multipleportions for distant vision, thereby providing a wide horizontal fieldof view with a moderate thickness of lens. Our lens will, therefore, beespecially suitable for the visual requirements lof persons requiringstrong concave or convex lenses. Such lenses are called for in extremesof myopiaand hyperopia, as Well as in post-cataract or aphakic cases. It

vwill be obvious that, while these multiple fields have independentoptical centers, these centers are not necessarily located upon the sameline. The number of elds is not necessarily limited to three, `but canbe increased to ve or more, as is most suitable in view of theparticular requirements of the wearer.

It will be understood that we desire to comprehend within our inventionsuch modifications as may be necessary to adapt it to varying conditionsand uses.

Having thus fully described our invention, what we claim as new anddesire to secure by Letters Patent is:

1. A lenticular ophthalmic lens comprising a body portion having anon-visual border portion, and .a plurality of visual-portions ofsubstantially the -same focal power, said visual portions comprising acentral iield and lateral elds abutting said central field on theopposite sides thereof.

2. A lenticular ophthalmic lens comprising a body portion having anon-visual border portion, and a plurality of abutting visual portionsof substantially the same focal power and arranged adjacent to oneanother.

4. A lenticular ophthalmic lens comprising a body portion having anon-visual border portion,

vand a plurality of abutting visual portions of substantially the samefocal power and arranged adjacent to one another in abuttingrelationship.

5. A lenticular ophthalmic lens comprising a body portion having anon-visual border portion and a plurality of intersecting concavities ofsubstantially the same surface curvatures, and an inserted portion of ahigher index of refraction secured in 'said concavities.`

6. A lenticular ophthalmic lens comprising a body portion having anon-visual border portion, and a plurality of intersecting concavities,one of said concavities being of a different surface curvature, theremaining concavities being of the same surface curvature whereby toprovide a lenticular lens having a multiple distant-vision portion and asingle near-vision portion.

7. A lenticular ophthalmic lens comprising a body portion having anon-visual border portion and a plurality of intersecting concavities,one of said concavities being of a. differentsurface curfvature, theremaining concavities being of the same surface curvature, and aninserted portion of a higher index of refraction secured in saidconcavities. I

8. A lenticular ophthalmicv lens comprising a body portion having anon-visual bodyiportion, a plurality of abutting distant-visionportions, and a near-vision portion associated therewith.

9. A lenticular ophthalmic lens. comprising a. body portion having anon-visual border portion, and a plurality of distant vision portionsarranged to abut one another on straight lines, said distant-visionportions being arranged adjacent to one another in a horizontaldirection.

EDWARD CULVER.

ALFRED HENRY EMERSON. 20

